Since no one who has Scrivener running on Catalina has jumped in, I though I'd try to offer some limited help (I don't have either).
Some Ideas:
- Most likely a Catalina issue -- see TIP: Resolving Catalina (and Mojave) Accessibility and Security Permissions Issues
- If this is a new version of Scrivener, it is possible that the target window ("Binder") has been changed to use a non-standard window that KM can't see.
- To find out, you can run this macro: MACRO: List Properties of Front Window
I know we have a number of Forum members who use Scrivener, so maybe one of them will jump in with more specific help.
Good luck, and let us know how it goes.